U.S. patent application number 12/386407 was filed with the patent office on 2009-10-29 for liquid crystal display.
This patent application is currently assigned to Tsinghua University. Invention is credited to Shou-Shan Fan, Wei-Qi Fu, Kai-Li Jiang, Liang Liu.
Application Number | 20090268139 12/386407 |
Document ID | / |
Family ID | 41214637 |
Filed Date | 2009-10-29 |
United States Patent
Application |
20090268139 |
Kind Code |
A1 |
Liu; Liang ; et al. |
October 29, 2009 |
Liquid crystal display
Abstract
A liquid crystal display includes a first substrate, a first
alignment layer, a liquid crystal layer, a second alignment layer,
and a second substrate opposite to the first substrate, a first
electrode and a second electrode. The liquid crystal layer is
sandwiched between the first substrate and the second substrate.
The first alignment layer is located on the first substrate and
face the liquid crystal layer. The second alignment layer is
located on the second substrate and face the liquid crystal layer.
Furthermore, at least one of the first and second alignment layers
comprises a carbon nanotube structure, and the carbon nanotube
structure is electrically connected to the first electrode and the
second electrode.
Inventors: |
Liu; Liang; (Beijing,
CN) ; Jiang; Kai-Li; (Beijing, CN) ; Fu;
Wei-Qi; (Beijing, CN) ; Fan; Shou-Shan;
(Beijing, CN) |
Correspondence
Address: |
PCE INDUSTRY, INC.;ATT. Steven Reiss
288 SOUTH MAYO AVENUE
CITY OF INDUSTRY
CA
91789
US
|
Assignee: |
Tsinghua University
Beijing City
CN
HON HAI Precision Industry CO., LTD.
Tu-Cheng City
TW
|
Family ID: |
41214637 |
Appl. No.: |
12/386407 |
Filed: |
April 16, 2009 |
Current U.S.
Class: |
349/123 ;
977/742 |
Current CPC
Class: |
G02F 2202/36 20130101;
G02F 1/1337 20130101 |
Class at
Publication: |
349/123 ;
977/742 |
International
Class: |
G02F 1/1337 20060101
G02F001/1337 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 25, 2008 |
CN |
200810066689.2 |
Claims
1. A liquid crystal display comprising: a first substrate; a second
substrate; a liquid crystal layer located between the first
substrate and the second substrate; a first alignment layer located
on a surface of the first substrate, the first alignment layer
comprising a first carbon nanotube structure; a second alignment
layer located on the second substrate; and a first electrode and a
second electrode, and the first electrode and the second electrode
are electrically connected to the first carbon nanotube
structure.
2. The liquid crystal display as claimed in claim 1, wherein the
first carbon nanotube structure comprises a plurality of carbon
nanotubes arranged along the same direction.
3. The liquid crystal display as claimed in claim 1, wherein the
first carbon nanotube structure comprises at least one carbon
nanotube film comprising a plurality of carbon nanotubes parallel
to each other.
4. The liquid crystal display as claimed in claim 3, wherein the
first carbon nanotube structure comprises at least two stacked
carbon nanotube films, and an angle between the aligned directions
of the carbon nanotubes in adjacent carbon nanotube layers is equal
to approximately 0 degrees.
5. The liquid crystal display as claimed in claim 3, wherein the
carbon nanotube film comprises a plurality of successively oriented
carbon nanotube segments joined end-to-end by van der Waals
attractive force therebetween.
6. The liquid crystal display as claimed in claim 5, wherein each
carbon nanotube segment comprises of a plurality of carbon
nanotubes, the carbon nanotubes have a substantial same length, and
adjacent carbon nanotubes are attracted by van der Waals attractive
force therebetween.
7. The liquid crystal display as claimed in claim 3, wherein a
plurality of gaps are defined between the carbon nanotubes.
8. The liquid crystal display as claimed in claim 1, wherein the
first carbon nanotube structure comprises a plurality of carbon
nanotube wires, and the carbon nanotube wires are located in
parallel to each other.
9. The liquid crystal display as claimed in claim 8, wherein each
carbon nanotube wire comprises a plurality carbon nanotubes joined
end-to-end by van der Waals attractive force.
10. The liquid crystal display as claimed in claim 8, wherein the
carbon nanotube wire is twisted.
11. The liquid crystal display as claimed in claim 8, wherein a
plurality of gaps are defined between the carbon nanotube
wires.
12. The liquid crystal display as claimed in claim 1, wherein the
first electrode and the second electrode are located on the surface
of the first substrate, and the first electrode and the second
electrode are located in parallel and extend along a first
direction.
13. The liquid crystal display as claimed in claim 12, wherein the
second alignment layer comprises a second carbon nanotube
structure.
14. The liquid crystal display as claimed in claim 13, further
comprising a third electrode, the third electrode is electrically
connected to the second carbon nanotube structure, and the third
electrode is located on the surface of the second substrate and
extends along a second direction.
15. The liquid crystal display as claimed in claim 14, further
comprising a fourth electrode, the fourth electrode is electrically
connected to the second carbon nanotube structure, and the fourth
electrode is located on the surface of the second substrate and
parallel to the third electrode.
16. The liquid crystal display as claimed in claim 14, wherein the
first direction crosses the second direction.
17. The liquid crystal display as claimed in claim 16, wherein the
first direction is perpendicular to the second direction.
18. The liquid crystal display as claimed in claim 1, wherein the
first alignment layer further comprises a fixing layer on the first
carbon nanotube structure.
19. The liquid crystal display as claimed in claim 18, wherein the
material of the fixing layer is comprises of a material that is
selected from the group consisting of diamond, silicon nitrogen,
hydride of random silicon, silicon carbon, silicon dioxide,
aluminum oxide, tin oxide, cerium oxide, zinc titanate, and indium
titanate, polyethylene ethanol, polyamide, polymethyl methacrylate,
and polycarbonate.
20. The liquid crystal display as claimed in claim 1, further
comprising at least one polarizer located on surface of the first
substrate, at least one polarizer located the second substrate or
at least one polarizer located on both the first and second
substrate.
Description
RELATED APPLICATIONS
[0001] This application is related to applications entitled "LIQUID
CRYSTAL DISPLAY", filed ______ (Atty. Docket No. US19075); "LIQUID
CRYSTAL DISPLAY", filed ______ (Atty. Docket No. US21521). The
disclosures of the above-identified applications are incorporated
herein by reference. The application is also related to co-pending
applications entitled "LIQUID CRYSTAL DISPLAY SCREEN", filed Nov.
20, 2008 (Atty. Docket No. US18573); "LIQUID CRYSTAL DISPLAY
SCREEN", filed Nov. 20, 2008 (Atty. Docket No. US18574); "METHOD
FOR MAKING LIQUID CRYSTAL DISPLAY SCREEN", filed Nov. 20, 2008
(Atty. Docket No. US18575); "LIQUID CRYSTAL DISPLAY SCREEN", filed
Nov. 20, 2008 (Atty. Docket No. US19048); "LIQUID CRYSTAL DISPLAY
SCREEN", filed Nov. 20, 2008 (Atty. Docket No. US19049); and
"LIQUID CRYSTAL DISPLAY SCREEN", filed Nov. 20, 2008 (Atty. Docket
No. US19050); "METHOD FOR MAKING LIQUID CRYSTAL DISPLAY SCREEN",
filed Nov. 20, 2008 (Atty. Docket No. US19051).
BACKGROUND
[0002] 1. Technical Field
[0003] The present disclosure relates to liquid crystal displays
and, particularly, to a carbon-nanotube-based liquid crystal
display.
[0004] 2. Discussion of Related Art
[0005] A liquid crystal display (LCD) generally includes a first
substrate, a second substrate, and a liquid crystal layer. The
first substrate is located parallel to the second substrate. The
liquid crystal layer including a plurality of liquid crystal
molecules is located between the first substrate and the second
substrate. A first transparent electrode layer and a first
alignment layer are formed on a surface of the first substrate
facing toward the liquid crystal layer. A first polarizer is formed
on an opposite surface of the first substrate that faces away from
the liquid crystal layer. A second transparent electrode layer and
a second alignment layer are formed on a surface of the second
substrate that faces toward the liquid crystal layer. A second
polarizer is formed on an opposite surface of the second substrate
that faces away from the liquid crystal layer.
[0006] When no voltage is supplied to the liquid crystal display,
light can pass through the liquid crystal display. When voltage is
supplied, light cannot pass through the liquid crystal display.
Thus, when a predetermined voltage is selectively applied to
different pixels defined in the liquid crystal display, a picture
can be shown.
[0007] However, for many reasons, the liquid crystal display cannot
perform at low temperature environment. Firstly, since the
threshold voltage of the liquid crystal display is related to the
temperature, the threshold voltage of the liquid crystal display
will increase as the external temperature decreases. A change in
the threshold voltage will deteriorate the contrast of the liquid
crystal display. Secondly, the viscosity of the liquid crystal
molecules in the liquid crystal layer will increase as the external
temperature decreases. The liquid crystal molecules become hard to
transit its phases and then the response of the liquid crystal
display becomes slow.
[0008] Conventionally, in order to overcome the above problems, a
heating layer can be located on the substrate to increase an
operating temperature of the liquid crystal display. The heating
layer is usually an indium-tin oxide transparent conductive layer.
However, the indium-tin oxide transparent conductive layer is not
very efficient for heating and consumes space, which requires that
the liquid crystal display be thicker.
[0009] What is needed, therefore, is to provide a thin liquid
crystal display that can perform at low temperatures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] Many aspects of the present liquid crystal display can be
better understood with reference to the following drawings. The
components in the drawings are not necessarily drawn to scale, the
emphasis instead being placed upon clearly illustrating the
principles of the present liquid crystal display.
[0011] FIG. 1 is a schematic, isometric view of a liquid crystal
display in accordance with a first embodiment.
[0012] FIG. 2 is a cross-sectional schematic view of the liquid
crystal display of FIG. 1, taken along a line II-II.
[0013] FIG. 3 is a cross-sectional schematic view of the liquid
crystal display of FIG. 1, taken along a line III-III.
[0014] FIG. 4 is a Scanning Electron Microscope (SEM) image of a
carbon nanotube film in accordance with the first embodiment.
[0015] FIG. 5 is a structural schematic view of a carbon nanotube
segment of the carbon nanotube film of FIG. 4.
[0016] FIG. 6 is a Scanning Electron Microscope (SEM) image of an
untwisted carbon nanotube wire in accordance with the first
embodiment.
[0017] FIG. 7 is a Scanning Electron Microscope (SEM) image of a
twisted carbon nanotube wire in accordance with the first
embodiment.
[0018] FIG. 8 is a schematic, isometric view of a liquid crystal
display in accordance with a second embodiment.
[0019] Corresponding reference characters indicate corresponding
parts throughout the several views. The exemplifications set out
herein illustrate at least one embodiment of the present liquid
crystal display, in at least one form, and such exemplifications
are not to be construed as limiting the scope of the disclosure in
any manner.
DETAILED DESCRIPTION
[0020] References will now be made to the drawings to describe, in
detail, various embodiments of the present liquid crystal
display.
[0021] Referring to FIGS. 1, 2, and 3, a liquid crystal display 300
in the first embodiment includes a first substrate 302, a first
alignment layer 304, a liquid crystal layer 338, a second alignment
layer 324, and a second substrate 322. The liquid crystal layer 338
is sandwiched between the first substrate 302 and the second
substrate 322. The first alignment layer 304 is located on the
first substrate 302 adjacent to the liquid crystal layer 338. A
plurality of parallel first grooves 308 is defined in a surface of
the first alignment layer 304 facing the liquid crystal layer 338.
The second alignment layer 324 is located on the second substrate
322 adjacent to the liquid crystal layer 338. A plurality of
parallel second grooves 328 is defined in a surface of the second
alignment layer 324 facing the liquid crystal layer 338. An
alignment direction of the first grooves 308 is perpendicular to an
alignment direction of the second grooves 328.
[0022] At least one of the first alignment layer 304 and second
alignment layer 324 includes a carbon nanotube structure. In the
present embodiment, both the first alignment layer 304 and second
alignment layer 324 include a carbon nanotube structure.
[0023] The carbon nanotube structure in first alignment layer 304
is electrically connected to at least two electrodes. The
electrodes are used to supply voltage to the carbon nanotube
structure. Furthermore, the carbon nanotube structure in the second
alignment layer 324 is electrically connected to at least one
electrode. In the present embodiment, the liquid crystal display
300 includes a first electrode 306, a second electrode 307 and a
third electrode 326. The first electrode 306 and the second
electrode 307 are located separately and electrically connected to
the carbon nanotube structure in the first alignment layer 304. The
third electrode 326 is electrically connected to the carbon
nanotube structure in the second alignment layer 324.
[0024] The carbon nanotube structure includes a plurality of carbon
nanotubes arranged along the same direction. The carbon nanotubes
can be single-walled carbon nanotubes, double-walled carbon
nanotubes, multi-walled carbon nanotubes or any combination
thereof. Diameters of the single-walled carbon nanotubes range from
about 0.5 to about 10 nanometers. Diameters of the double-walled
carbon nanotubes range from about 1 to about 50 nanometers.
Diameters of the multi-walled carbon nanotubes range from about 1.5
to about 50 nanometers. Each carbon nanotube structures can include
one or more carbon nanotube films, or a plurality of carbon
nanotube wires.
[0025] In one embodiment, the carbon nanotube structure includes
one carbon nanotube film. Referring to FIGS. 4 and FIG. 5, the
carbon nanotube film includes a plurality of successively oriented
carbon nanotube segments 143 joined end-to-end by van der Waals
attractive force therebetween. Each carbon nanotube segment 143
includes a plurality of carbon nanotubes 145 parallel to each
other, and combined by van der Waals attractive force therebetween.
The carbon nanotube segments 143 can vary in width, thickness,
uniformity and shape. The carbon nanotubes 145 in the carbon
nanotube film 143 are oriented along a preferred orientation.
[0026] The carbon nanotube film can be formed by the substeps of:
(a) providing a super-aligned carbon nanotube array on a substrate;
(b) selecting two or more carbon nanotubes having a predetermined
width from the super-aligned array of carbon nanotubes; and (c)
pulling the carbon nanotubes to form carbon nanotube segments that
are joined end to end. The carbon nanotube segments can be pulled
at an uniform speed to achieve a uniform carbon nanotube film. The
width and length of the carbon nanotube film is dependent on the
size of the carbon nanotube array. In one embodiment, when the
substrate is a 4-inch P-type silicon wafer as in the present
embodiment, the width of the carbon nanotube film is in a range
from about 0.5 nanometers to about 10 centimeters, and the
thickness of the carbon nanotube film is in a range from about 0.5
nanometers to about 100 microns. The length of the carbon nanotube
film can be larger than about 10 meters.
[0027] In other embodiments, the carbon nanotube structures may
include at least two stacked carbon nanotube films. Adjacent carbon
nanotube films are held in contact with each other by van der Waals
attractive force therebetween. An angle .alpha. between the
preferred orientations of the carbon nanotubes in two adjacent
carbon nanotube films is equal to approximately 0 degrees.
[0028] In another embodiment, the carbon nanotube structure may
include a plurality of carbon nanotube wires. The carbon nanotube
wires are located parallel to each other. The carbon nanotube wire
can be in twisted form or in untwisted form. The untwisted carbon
nanotube wire is formed by treating the carbon nanotube film with
an organic solvent. Specifically, the entire surface of the carbon
nanotube film is soaked in volatile organic solvent. After being
soaked in the organic solvent, the adjacent parallel carbon
nanotubes in the carbon nanotube film will be bundled together
because the surface tension of the organic solvent. This causes the
carbon nanotube film to shrink into untwisted carbon nanotube wire
when the organic solvent vaporizes. Referring to FIG. 6, an
untwisted carbon nanotube wire includes a plurality of carbon
nanotubes substantially oriented along the same direction (i.e., a
direction along the length of the untwisted carbon nanotube wire).
Specifically, the carbon nanotubes are substantially parallel to
the axis of the untwisted carbon nanotube wire. Length of the
untwisted carbon nanotube wire can be arbitrarily set as desired. A
diameter of the untwisted carbon nanotube wire is in a range from
about 0.5 nanometers to about 100 micrometers.
[0029] The twisted carbon nanotube wire is formed by twisting a
carbon nanotube film. In the examplarly embodiment, the twisted
carbon nanotube wire is formed by using a mechanical force to turn
the two ends of the carbon nanotube film in opposite directions.
Referring to FIG. 7, a twisted carbon nanotube wire includes a
plurality of carbon nanotubes oriented around an axial direction of
the twisted carbon nanotube wire in a helix pattern.
[0030] Further, the twisted carbon nanotube wire can be treated
with a volatile organic solvent. After being soaked is the organic
solvent, the adjacent parallel carbon nanotubes in the twisted
carbon nanotube wire will be bundled together, due to the surface
tension of the organic solvent when the organic solvent vaporizes.
As a result, the specific surface area of the twisted carbon
nanotube wire will decrease. The density and the strength of the
twisted carbon nanotube wire will be increased.
[0031] Referring to FIGS. 2, 3, the liquid crystal display 300
further includes a fixing layer. The fixing layer is located on the
carbon nanotube structure and faces the liquid crystal layer. In
the present embodiment, the first alignment layer 304 includes a
first carbon nanotube structure 304a and a first fixing layer 304b;
and the second alignment layer 324 includes a second carbon
nanotube structure 324a and a second fixing layer 324b. Due to the
first carbon nanotube structure 304a having a plurality of parallel
and uniform gaps, when the first fixing layer 304b is formed on the
first carbon nanotube structure 304a, the first grooves 308 are
formed on surfaces of the first fixing layer 304b. Due to the
second carbon nanotube structure 324a having a plurality of
parallel and uniform gaps, when the second fixing layer 324b is
formed on the second carbon nanotube structure 324a, the second
grooves 328 are formed on surfaces of the second fixing layer
324b.
[0032] In order to fabricate first grooves 308 that are
perpendicular to the second grooves 328, the arranged direction of
the carbon nanotubes in the first alignment layer 304 are
perpendicular to the arranged direction of the carbon nanotubes in
the second alignment layer 324. For example, the carbon nanotubes
in the first alignment layer 304 are each aligned parallel to an
X-axis, and the carbon nanotubes in the second alignment layer 324
are each aligned parallel to a Z-axis. A thickness of each of the
first alignment layer 304 and the second alignment layer 324 is in
a range from about 1 micrometer to about 50 micrometers.
[0033] The fixing layers 304b, 324b can be made of the materials
selected from the group consisting of diamond, silicon nitrogen,
hydride of random silicon, silicon carbon, silicon dioxide,
aluminum oxide, tin oxide, cerium oxide, zinc titanate, and indium
titanate. The fixing layers 304b, 324b can be fabricated by
evaporating, sputtering, or plasma enhanced chemical vapor
deposition. Alternatively, the fixing layers 304b, 324b can be made
of the materials selected from the group consisting of polyethylene
ethanol, polyamide, polymethyl methacrylate, and polycarbonate. The
fixing layers 304b, 324b are sprayed on the first carbon nanotube
structure 304a and the second carbon nanotube structure 324a. A
thickness of the fixing layers is in a range from about 20
nanometers to about 2 micrometers.
[0034] The first substrate 302 and the second substrate 322 can be
made of materials selected from the group comprising of glass,
quartz, diamond, and plastics. In the present embodiment, the first
substrate 302 and the second substrate 322 are made of flexible
materials, such as cellulose triacetate (CTA). According to
user-specific needs, the first substrate 302 and the second
substrate 322 can be made of different suitable.
[0035] The liquid crystal layer 338 includes a plurality of
cigar-shaped liquid crystal molecules. The liquid crystal layer 338
can also be made of other liquid crystal materials, which are
generally used in the present technology. Furthermore, a plurality
of supporters (not shown) can be located between the first
alignment layer 304 and the second alignment layer 324. The
supporter can be a small ball made of polyethylene. A diameter of
the ball ranges from about 1 to about 10 micrometers. In the
present embodiment, the diameter of the ball is 5 micrometers.
[0036] The shape of the first electrode 306, the second electrode
307 and the third electrode 326 is arbitrary. In the present
embodiment, each of the electrodes is strip-shaped. The first
electrode 306 and the second electrode 307 are located in parallel
and extend along a first direction. The first electrode 306 and the
second electrode 307 are located on the surface of the first
alignment layer 304 adjacent to the first substrate 302. The first
electrode 306 and the second electrode 307 are located on the two
opposite ends of the first substrate 302. The third electrode 326
is located on the surface of the second alignment layer 324
adjacent to the second substrate 322 and extends along a second
direction. The first direction and the second direction intersect
with each other. In present embodiment, the first direction is
perpendicular with the second direction. Also, the electrodes 306,
307, 326 can be located on the surface of the alignment layer 304,
324 far away from the substrate 302, 322 or on the surface of the
fixing layer 304b, 324b far away from the liquid crystal layer
338.
[0037] The first alignment layer 304 of the liquid crystal display
300 can be heated if needed as described below.
[0038] When the liquid crystal display 300 does not need to be
heated, the third electrodes 326 is kept at zero, and the first
electrode 306 and the second electrode 307 are controlled by
information source to allow the liquid crystal display 300 work.
When the liquid crystal display 300 needs to be heated, the second
electrode 307, electrically connected to the first carbon nanotube
structure 304a, is in any one of four states. In the first state
the second electrode 307 pre-heats the liquid crystal display 300
before it operates, by applying a steady pre-determined amount of
direct current to the first carbon nanotube structure 304a to heat
the liquid crystal display 300 up to a predetermined temperature.
The second electrode 307 enters the second state to keep the liquid
crystal display 300 heated while it is in an "off" state, by
applying direct current pulses to the first carbon nanotube
structure 304a. In this state, a compensation voltage such as 2.5 V
should be applied to the third electrode 326 to keep the liquid
crystal display 300 in an "off" state. The second electrode 307
enters the third state when the liquid crystal display 300 is in
transition between the "off" state and "on" state, and heats the
display 300 by applying a high frequency alternating current to the
first carbon nanotube structure 304a. Because the relaxation time
of the liquid crystal display 300 between the "off" state and "on"
state is a matter of microseconds, the frequency of the high
frequency current should be above 10 kilohertz. While the display
300 is in the "on" state the second electrode 307 enters the fourth
state and does not apply current.
[0039] Referring to FIG. 8, the liquid crystal display 400 in the
second embodiment includes a first substrate 402, a first alignment
layer 404, a liquid crystal layer 438, a second alignment layer
424, a second substrate 422, a first electrode 406, a second
electrode 407, a third electrode 426. The liquid crystal display
400 in the second embodiment has a similar structure with the
liquid crystal display 300 in the first embodiment. The difference
between the liquid crystal display 400 and the liquid crystal
display 300 is that the liquid crystal display 400 includes a
fourth electrode 427 used to supply voltage to the carbon nanotube
structure in the second alignment layer 424. The fourth electrode
427 and the third electrode 426 are located in parallel.
[0040] The alignment layer 404, 424 of the liquid crystal display
400 can be heated if needed as described below. While the liquid
crystal display 400 does not need to be heated, the first
electrodes 426, 427 are kept at zero, and the electrodes 406, 407
are controlled by information source to allow the liquid crystal
display 400 work. While the liquid crystal display 400 needs to be
heated, the heating process is similar with the heating process of
the liquid crystal display 300. The difference is that a current is
applied to the carbon nanotube structure in the both first
alignment layer 404 and second alignment layer 424 at same time. In
the present embodiment, because the voltage applied to the fourth
electrode 427 can keep the liquid crystal display 400 in an "off"
state, no additional compensation voltage should be applied to the
third electrode 426.
[0041] When the liquid crystal display 400 needs to be heated, the
second electrode 407, electrically connected to the first carbon
nanotube structure, is in any one of four states. In the first
state the second electrode 407 pre-heats the liquid crystal display
400 before it operates, by applying a steady pre-determined amount
of direct current to the carbon nanotube structure in the first
alignment layer 404 to heat the liquid crystal display 400 up to a
predetermined temperature. In this state, a voltage, such as 5 V,
is applied to the fourth electrode 427 to apply a steady
pre-determined amount of direct current to the carbon nanotube
structure in the second alignment layer 424 to heat the liquid
crystal display 400. The second electrode 407 enters the second
state to keep the liquid crystal display 400 heated while it is in
an "off" state, by applying direct current pulses to the carbon
nanotube structure in the first alignment layer 404. In this state,
a voltage such as 5 V is applied to the fourth electrode 427 to
apply a steady pre-determined amount of direct current to the
carbon nanotube structure in the second alignment layer 424 to heat
the liquid crystal display 400 and no additional compensation
voltage should be applied to the third electrode 426. The second
electrode 407 enters the third state when the liquid crystal
display 400 is in transition between the "off" state and "on"
state, and heats the display 400 by applying a high frequency
current to the carbon nanotube structure in the alignment layer
404, 424. Because the relaxation time of the liquid crystal display
400 between the "off" state and "on" state is a matter of
microseconds, the frequency of the high frequency current should be
above 10 kilohertz. While the display 400 is in the "on" state the
second electrode 407 enters the fourth state and does not apply
current.
[0042] Due to the carbon nanotube having excellent conductive
properties, thermal stability, high thermal radiation efficiency
and large specific surface area, the carbon nanotube structure of
the present embodiment can served as a perfect black body. The
thermal response speed of the carbon nanotube structure is high due
to its small heat capacity of per unit area which less than
1.7.times.10.sup.-6 J/(CM.sup.2K). A carbon nanotube film with a
thickness of about 1 micrometer to about 1 millimeter can reach its
highest surface temperature within 1 second. A drawing carbon
nanotube film can reach its highest surface temperature within 0.1
milliseconds.
[0043] Because the carbon nanotubes provide each carbon nanotube
structure with good electrical conductivity, each carbon nanotube
structure can be used to conduct electricity and thereby replace a
conventional transparent electrode layer. Specifically, the carbon
nanotube structure can act as both an alignment layer and an
electrode layer. This simplifies the structure and reduces the
thickness of the liquid crystal display, thereby enhancing the
efficiency of usage of an associated backlight while retaining all
functionality. Additionally, it forms a plurality of parallel gaps
in carbon nanotube structure without the use of mechanical
treatments (such as rubbing the carbon nanotube film). Thus, the
conventional art problem of electrostatic charge and dust
contamination can be avoided, while the corresponding alignment
layers have improved alignment quality.
[0044] Moreover, by covering a fixing layer on the carbon nanotube
structure, this prevents the carbon nanotube structure of the
alignment layer from falling off when the carbon nanotube structure
is in contact with the liquid crystal layer. Therefore, the liquid
crystal display has improved durability and an excellent
arrangement of liquid crystal molecules.
[0045] Because the carbon nanotubes in each carbon nanotube
structure are arranged in parallel, the carbon nanotube structure
has a light polarization characteristic, and as a result, can be
used to replace a conventional polarizer. However, at least one
polarizer can be located on a surface of the first substrate that
faces away from the liquid crystal layer, and/or on a surface of
the second substrate that faces away from the liquid crystal
layer.
[0046] The liquid crystal display provided in the present
embodiment is a single-pixel liquid crystal display. By arranging a
number of the liquid crystal displays in a predetermined fashion, a
multi-pixel liquid crystal display could be obtained. The
multi-pixel liquid crystal display could have the same or different
substrate.
[0047] The liquid crystal display in the present embodiment has the
many advantages including the following. Firstly, the carbon
nanotube structure can be used as a heating layer, thus the liquid
crystal display can perform at low external temperatures. Secondly,
the carbon nanotube structure can be used as a heating layer and an
alignment layer at the same time, thus simplify the structure of
the liquid crystal display and reduce the thickness of the liquid
crystal display. Thirdly, the carbon nanotube structure can act as
both an alignment layer and an electrode layer, thus further
simplify the structure of the liquid crystal display and reduce the
thickness of the liquid crystal display. Therefore, the liquid
crystal display has improved durability and improved arrangement of
liquid crystal molecules.
[0048] Finally, it is to be understood that the above-described
embodiments are intended to illustrate rather than limit the
disclosure. Variations may be made to the embodiments without
departing from the spirit of the disclosure as claimed. The
above-described embodiments illustrate the scope of the disclosure
but do not restrict the scope of the disclosure.
* * * * *